Connecting device



Nov. 8, 1932. H. J. FRANK 1,887,090

CONNECTING DEVICE Filed May 5. 1950 INVENTOR.

A TTORNEY.

i Patented Nov. 8, 1932 UNITED. STATES PATENT OFFICE HARRISON J. L. FRANK, OF HIGHLAND PARK, MICHIGAN, ASSIGNOR TO BIILL DOG ELECTRIC PRODUCTS COMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF 'WEST VIRGINIA.

CONNECTING DEVICE Application filed Kay 5,

This invention relates to electrical connecting devices and more particularly to devices adapted to connect certain electrical parts to a bus bar.

The application of Harrison J. L.Frank, Ser. No. 353,343, filed April 8, 1929, of which this application is in part, a continuation, discloses a switch block which is adapted to be secured to a panel board having vertically extending bus bars thereon'and also discloses means for electrically connecting a device inside the switch block to one of the bus bars.

Devices of this character have been widely used and generally comprise nothing more than a screw bolt which is passed through a perforation in the electrically conducting part and threaded into the bus bar. \Vhere large currents are involved, the use of a screw bolt alone is objectionable for many reasons, the main reason being that the bolt does not offer suflicient contact surface or conducting capacity in itself, even if it be made very large. Further, when a large bolt is used, the holes in the contact and bus bar must also be large and consequentlythe cross sectional conducting area of these parts is,

considerably decreased by reason of the presence of these large holes.

It has become the practice, where large currents are used to supplement the bolt with a bushing, washer or other conducting means located between the electrically conducting part and-the bus bar, utilizing the screw to clamp the mcmberstogether. This practice is very undesirable, since the bushing or washer may dropofl the bolt and short circuit the bus bars.

If, in attempting to correct this, the bushing or washer is threaded on the bolt after it has passed through the perforation in the electrically conducting part, the bushing will act as a check nut and will lock the bolt, preventing the bolt from properly engaging the bus bar and clamping the elements together.

An object of this invention, therefore, is a device for electrically connecting such parts and which includes the simplest form of connecting means, namely, a screw bolt.

1930. Serial No. 449,706.

Another object is a connecting means which is quickly detachable from the bus bar but which can be securely engaged therewith for contact making purposes.

A further object is a connecting means which is readily releasable from the bus bar and which permits ready removal of the switch block from the bus bars, without necessity of tearing down the switch board or bus bars.

A further object is a connecting device of this character which may be successfully used to connect a part to a bus bar, even though the space between the electrically conducting part and the bus bar is inaccessible.

A further object of this invention is a connecting means of this character which insures the elements being properly clamped together even though the connecting means was notcompletely assembled on the electrically conducting part.

A still further object of this is a connecting means of this character which allows the electrically conductin part, the connecting member and the bus ar, to be clamped together and wherein the connecting member is retained on the part while placing the part over the bus bar.

A further object is a connecting device of this character which is releasably secured'to the switch block, so that when the latter is being mounted in place, a connector cannot be lost and cannot cause short circuiting.

A further object is a connecting device ofcientin its operation and simple in its construction.

Still other objects will readily occur to those skilled in the art upon reference to the following description and the accompanying drawing in which Fig. 1 shows a section of a panel board is shown at 11 as extending vertically there-' on. A switch block 12, of insulating material, has secured thereto, by means of the screws 13, the electrically conducting part,

which in this case is the strap 14, the latter being electrically connected to the bus bar 11 by means comprising the screw-bolt 17 and the bushing 18. This means may also be used to secure the strap 14 and the block 12 to thebus bar11, although in the application previously referred to, independent mountin and securingmeans are shown.

In the specific form of the connecting means shown in Fig. 1, screw bolt 17 has a threaded portion 17a and a smaller diameter, unthreaded portion 17 b. The bushing 18 is interna-ll threaded at 18a for a portion of its lengt the threads 17a and 18a being adapted to cooperate, and the bushing 18 is also provided with a larger diameter, un-

threaded portion 18?).

the st-rap'14 to the bus bar 11, the bolt 17 is The use of the connecting means of Fig. 1 will be quite obvious.

When it is desired to mount the switch block 12 upon the'panel 10 and to connect passed thru the aperture 19 in the strap and the bushing 18 is threaded upon the bolt 17 until its threaded portion 18a passes beyond thethreaded portion 17 act the bolt, whereupon the bushing 18 will be loosely secured to the bolt in such a manner that accidental se aration of these two parts is prevented.

olt 17 is then threaded into the tapped hole 19a of the bus bar 11 so as to extend into hole 19?) of the panel board 10. Bushing 18 will not interfere with the operation, as will be observed, and when the legs 12a of the switch block 12 engage the panel board 10, so that further movement is prevented, bushing 18 will firmly engage on one side the bus bar 11 and on the other side the strap 14, so

as to electrically connect these parts.

It will be observed that when the switch block 12 is being mounted on the panel 10, the previously inserted bolt 17 and bushing 18 cannot readily and accidentally separate from the switch block 12, and short circuiting and loss of connecting parts is prevented in this manner.

It will also be observed that electrical con- I nection from bar 11 to strap 14 is made thru the bolt 17 and the bushing 18 which, combmed, give a cross section area great enough being peripherally to permit of the flow of heavy currents between these parts.

It will also be observed'that the operation of connecting strap 14 to the bus bar 11 is very simple, it being nothing more than the simple screw inserting operation.

The construction thus far described is shown in the application previously referred to and so far this-case may be regarded as a division thereof. However, it will be understood that various modifications of the connecting means of Fig. 1 may be provided and such means will now be described.

Fig. 2 discloses a connecting means wherein the bolt 27 is provided with a threaded portion 27a and an" unthreaded portion 27b. The bolt 27 is also provided with a plurality of tapped holes 270 peripherally and longitudinally spaced thereon and adapted to receive a set screw 27d passed thru one of the slots 28a in the bushing 28, these slots also and longitudinally spaced, so that any slot 28a and any threaded aperture 270 may be used, thus enabling the device to be rendered adjustable.

In this construction also the bushing 28 is first secured to the bolt 27 after the latter has been passed thru the aperture 19 in the strap 14, and the bolt 27 is then threaded into the bus bar.

Fig. 3 shows a connecting means wherein the means to connect the bushing 38 and the bolt 37 includes a helical groove 38a on the interior of the bushing which forms a locking means and an adjusting track for the pin 37d of the bolt 37.

In this construction, bolt 37 and bushing 38 are secured to each other after the bolt 37 has been passed thru strap 14, by .engaging the pin 3711 with the groove in the bushing 38 and rotating the latter for adjustment;

In Fig. 4 the securing means resembles the one of Fig. 3, except that the pin 48d is pro vided on the interior of the bushing the groove 47a is provided on the periphery of the bolt 47.

48 While I In Fig. 5 the-small diameter portion of the bolt 57 is surrounded by the split bushing 58, the latter being secured to the screw 57 after it has been inserted in the block by bending it to the shape shown in Fig. 6.

In F1 7 ,the bolt 17 is exactly like the one used in *ig. 1, and the bushing 18 is replaced by a U shaped member 68 made of a strap of copper, etc., and having a tapped hole 68a and an unthreaded hole 68?), corresponding to the portions 18a and 18b of Fig. 1.

It will be noted that in all of the construc-.

tions shown, except that of Fig. 2, the con- 12 nections are made entirely from' the front of the block 12. This is important, since the clearance between block 12 and bus bar 11 may be very small, or the bus bar 13 may be inaccessible except from the front, or blocks adjacent block 12 may prevent access to the bushing from the top or bottom side of the block 12, in all of which cases onl a connecting means accessible. entirely rom the front can be used.

It will also be observed that if bushing? 18 is only partially threaded on the bolt 17 the first threading operation whena block .12 is being mounted, will cause the bushing to thread upon the bolt until the clear portion 18?) is opposite the threads 17a, whereupon bolt 17 can be threaded into the bus bar. This is .due to the fact that the bushing will abut the bus bar, and friction therebetween caused by pressure of the block on the bushing and on the bus will hold the bushing from rotating. I

It will further be noted that the bushing tends to hold itself to the bolt and to hold the 20 bolt to the stra so that neither of them may drop out o the block when the latter is being mounted. I

' Further, 'it will be observed that the bushing tends to guide theend 17a of the bolt into the hole.19a of the bus bar, thus facilitating connection and preventing arcing between the screw and a bus bar when the latter happens to be live.

Further, it will be seen that whilethe words bus bar and part have been used throughout, that the connecting means shown is applicable to any spaced contacts, either of which may be regarded as a bus bar, if desired, and the other of which may be regarded as the part.

Now having described the invention and the preferred embodiment thereof, it is to be understood that the said invention is to be limited, not to the specific details herein set forthand illustrated, but only by the scope of the claims which follow: I

I claim f 1. In combination with an immovably mounted bus bar, a unit adapted to be mounted on said bus bar and having'a part to be electrically connected to said bus bar, said unit comprising an electrically conducting part, a screw bolt projecting 'therethru, and'having a manipulating head on the side thereof most remote from the bus bar and having an electrically conducting bushing on the bolt on the side of the part nearest the bus bar, said bushing being long enough to engage the bar and the part to electrically 55 connect them when the unit is mounted on the bar and the bolt threaded into the bus bar,'the bolt and the bushing having cooperating formations serving to hold them to,- gether and on the part, so that neither can free itself from the part as the unit is being mounted, the formations permitting the bushing to slide on the bolt. p

2. In combination with an immovably mounted .bus' bar, aunit mounted on said bus bar forwardly thereof and having on itsforward surface a part electrically connected to said busbar, said unit having an insulating wall between the part and the bus bar, a

sc'rew bolt projecting thru said part and said wall .and into said. bus bar and having a manipulating head forward of the part and an electrically conducting bushing removably secured on the bolt between the part and the bus bar and extending through the, wall for electrically contacting the part and the bus bar, the wall shielding the bus bar from the manipulator of the screw head.

3. In combination with an immovablymounted bus bar, a unit mounted on said bus bar forwardly thereof and having on its forward surface a part electrically connected to said bus bar, said unit having an insulat-- ing wall between the part and the bus bar, a screw bolt projecting thru said part and said wall and into said bus bar and having a manipulating head forward of the part and an electrically conducting bushing re movably but loosely secured on the bolt be tween the part and the bus bar and extending through the wall for electrically contacting the part and the bus bar, the wall shielding the bus bar from the manipulator of the screw head. r

4. In combination with an immovably mounted bus 'bar, a unit mounted on said bus bar forwardly thereof and having on its forward surface a part electrically connected to said bus bar, said unit having an insulating wall between the part and the bus bar, a screw bolt projecting thru said part and said wall and into said bus bar and having a manipulating head forward, of the part and an electrically conducting bushing removably but loosel and slidably secured on the bolt between t e part and the bus bar and extending through the wall for electrically contacting thepart of the bus bar, the wall shielding the bus bar from the manipulator of the screw head.

5. For mounting on an immovably mounted bus bar; a unit comprising a receptacle of insulating material and containing an electrically conducting part, a screw bolt projecting thru said part and the base, of the receptacle and adapted to be threaded into said bus bar and having a manipulating head disposed within the receptacle, a bolt securing bushing loosely secured on said bolt on the end thereof projecting thru the receptacle base, and electrically contacting said part through 'an aperture of the receptacle, said bushing being long enough to engage the part and the bus bar when the unit is mounted thereon, and also having formations preventin accidental separation thereof from said b0 t, said formations permitting said bolt being threaded tightly into said bus bar by means enga 'ng the bolt head, without interference 20111 the bushing on the bolt.

' HARRISON J. L. FRANK. 

